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NA49 Weekly Meeting12 Nov Status Got a referee response Overall very friendly, positive Working on updating the Paper Plan on resubmitting as soon as possible Minor changes to figures necessary We should be able to address the referee comments without too much difficulty Report of the Referee -- CV10102/Alt This is an excellent paper containing very significant results.Preliminary versions of these data have been widely discussed in the field and the presentation of the final versions and adetailed discussion of the procedure is very welcome. Overall,I found the text and figures to be of very high quality,a pleasure to read.

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NA49 Weekly Meeting12 Nov Response End of section I: An address of web link for accessing the data and acceptance tables would be helpful. We need to generate acceptance tables and publish them online EDH? Tim agreed to help a while ago

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NA49 Weekly Meeting12 Nov Response Section II A: The authors do not discuss the resolution of the E_veto counter. Presumably, this has a non-negligible dependence on beam energy. As a result, choosing the 3.5% of events with the smallest signals would sample a different range of event geometries at the different energies. This maybe an insignificant effect but is not discussed either way. This item needs some thought/work Claudia mentioned studies Dima did that could help addressing this point We did tests using 7% most central with mixed events created in 1% centrality bins. Got consistent results.

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NA49 Weekly Meeting12 Nov Response Section III A: The technique used in this paper to extract event-by-event ratios in the absence of the ability to provide reliable PID for individual tracks is quite clever. The reliability of the resulting ratios depends on the quality of the match between Equation 1 and the data in individual events. It would be very helpful if some quantitative measure,or typical graphical representation, of the correspondence between Equation 1 and real data events were included.The residuals in Fig 3 show a definite pattern which appears to be significant although it is obscured a bit by the choice of very fine binning. Assuming the residuals are the standard (data - fit) the pattern suggests that the peaks in the data are slightly wider but not as high as the fitted function. Perhaps this is related to the dE/dx width scaling mentioned in Section III C 4 but I could not find any discussion of it in the text. Since the integral of the curve is the only quantity used in the final result, this may not have a significant impact but the omission of any mention of this aspect of the fit stands out. Quantitative comparisons of single events and the PDFs are not possible because of the low pre event statistics We can add comments regarding the overall calibration and stability of the dE/dx estimation (e.g stability vs event multiplicity) and add a reference to my PhD thesis…

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NA49 Weekly Meeting12 Nov Response Start of section III C 1: I found the wording "definite mass” a bit confusing. I think what the authors mean is that they assign each particle a species (electron, pion, kaon, proton) randomly selected from the probability distribution for the particle's momentum and dE/dx. Will rephrase Section II C 1 and elsewhere: The use of "modified" mixed events is very creative but the wording is not consistent. In some places (see Fig 6 caption for one example) these samples are labeled "modified" but in other places (Fig 5 caption for example) they are simply labeled "mixed events". I suggest using the word "modified" or some similar qualifier or come up with a different term in every place where these non-standard mixed events are mentioned. Check for consistency and rephrase where neccessary

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NA49 Weekly Meeting12 Nov Response Page 15 line 4: The text mentions a systematic error of 0.2% but the gray band in figure 6 is +/- 0.4%.The vertical scale of figure 5 was supposedly chosen to make the point that the deviations are "small" but this makes the figure almost worthless and in particular obscures the small shift of mentioned in the text. This figure needs to be redone. Check with gunther, update text Pg 16 bottom-pg 17 top: The question of the "spike" at low K/pi values is a very significant one. The authors do a good job of describing in words how they investigated this effect but the presentation would be greatly strengthened with an additional figure. In particular, the spike itself is almost invisible in Figure 4. A version with that region expanded would be very helpful. Also, the authors claim about the absence of a spike at low k/pi in the ratio of data over mixed events is sufficiently important to deserve a figure. Could add figure. Dima and Tim have shown this ratio and zooms of the low K/pi ratio region.

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NA49 Weekly Meeting12 Nov Response There is no explanation of the error bars in Figure 7. In many cases, one is comparing two samples where one is a sub-set of the other and so errors need to be carefully evaluated. Some discussion would be helpful. Check text and add to it if neccessary Start of Section IV: The fact that the final presented values are the average of two different procedures should be mentioned more prominently, rather than being buried in the systematic error discussion of Section III C 5. Add text